Round Earth

The other day I mentioned that the Greeks knew the earth was round, and he
said, no they thought it was shaped like a cylinder. That's a new one on me
but this guy is usually right about things. Is he right?

"Sheldon" wrote in message
...
The other day I mentioned that the Greeks knew the earth was round, and he
said, no they thought it was shaped like a cylinder. That's a new one on
me
but this guy is usually right about things. Is he right?

There were different schools of thought (literally)
in ancient Greece. Around about the 6th century BC
one such school held a geocentric model in which the
Earth was a cylinder at the center of everything.

By the 4th century BC the Greeks had pretty much
decided that the Earth was a sphere.

Sheldon In the year 250 BC a Greek Math. teacher taught that the Earth
was round. He was asked how far away it was? "His answer was the
length of 60 Earths." He was very clever bert

On Jul 15, 5:17 am, (G=EMC^2 Glazier) wrote:
Sheldon In the year 250 BC a Greek Math. teacher taught that the Earth
was round. He was asked how far away it was? "His answer was the
length of 60 Earths." He was very clever bert


How far away what as?

Double-A

Double -A That Greek Math guy must have calculated the length of the
earth to be 8,000 miles;. He strung 60 Earth and came up with 240,000
miles. They claim he did it by the shadow the Earth makes on the moon.
I think it was a lucky guess bert

On Jul 15, 12:04 pm, (G=EMC^2 Glazier) wrote:
Double -A That Greek Math guy must have calculated the length of the
earth to be 8,000 miles;. He strung 60 Earth and came up with 240,000
miles. They claim he did it by the shadow the Earth makes on the moon.
I think it was a lucky guess bert


Not so much a guess. Some of those guys were really sharp back then.
Must have been all those natural whole grains and fibers they ate.

So then sometime in the middle ages someone must have come up with the
new flat Earth geometry, that it was thought would replace the common
sense but now outdated spherical Earth geometry of the unenlightened
ancients!

Double-A

"Sheldon" wrote in
:

The other day I mentioned that the Greeks knew the earth was round, and
he said, no they thought it was shaped like a cylinder. That's a new
one on me but this guy is usually right about things. Is he right?



Depends on which Greeks you are talking about. Pythagoras claimed the Earth
was spherical on philosophical grounds but offered no empirical support
AFAIK. Later Aristotle listed the following observations in support of the
concept of the Earth being spherical:

* It was noted that the masts and sails of ships come into view before the
hull at the horizon.

* Travelers going south see southern constellations rise higher above the
horizon.

* The shadow of Earth on the Moon during a lunar eclipse is always round no
matter what the position of the moon in the sky at the time of the eclipse.

This latter one is a clincher.

Later still, the scholar Eratosthenes determined the Earth's diameter to
within about ten percent by using noon observations of the solar altitude
taken at two cities close to the same longitude on the same day (Cyrene and
Alexandria).

Klazmon.

In article ,
Bob Officer wrote:

snip

Greek mythos commonly held that Atlas held the world (a sphere) upon
his shoulders.

Not exactly. In the orignal sources he's described either as bearing the
heavens or as keeping heaven and earth apart. Atlas was also credited
with introducing mortals to the science of astronomy.

--
Odysseus

"Odysseus" wrote in message...
news
In article ,
Bob Officer wrote:


snip

Greek mythos commonly held that Atlas held the world (a sphere) upon
his shoulders.

Yes, the *celestial* sphere or world, Bob.

Not exactly. In the orignal sources he's described either as bearing the
heavens or as keeping heaven and earth apart. Atlas was also credited
with introducing mortals to the science of astronomy.

--
Odysseus

Yes, it was Zeus' punishment for the Titan, Atlas,
after the Titans lost the war against the Olympians.
Classical art depicts Atlas holding up a *celestial*
sphere.

It was a combination of Atlas' connection to maps
by Lafreri and Mercator in the 16th century, and
the modern understanding of the Earth as a sphere
which has led to the many artistic renditions of
giant Atlas cradling Earth on his shoulders.

happy days and...
starry starry nights!

--
Are you sleeping?
Stars are waiting,
Shining high they wait for you.

Are you looking?
Stars are soaring,
Flashing, twinkling just for you.

http://www.youtube.com/watch?v=E5-kMXwkmPk

Indelibly yours,
Paine
http://www.savethechildren.org/
http://www.painellsworth.net

In article ,
Bob Officer wrote:

snip

The actual translation said Atlas' Doom was "to be burdened with the
weight of the world upon his shoulders". The separation of the
spheres didn't come 'til much later.

The actual translation of what?

In the _Odyssey_[1] Homer describes Atlas as "hold[ing] the tall pillars
which keep earth and heaven apart." The word here translated as "heaven"
is _ouranos_, which can refer to nothing but the celestial sphere;
"earth" is _gaia_. The two are clearly contrasted, and of course were
personified as the primordial pair of divine beings, the original union
of opposites. Considering that Homer dates from the eighth or ninth
century BCE, what source is this "much later" than?

Hesiod's _Theogony_[2] says "Atlas ... upholds the wide heaven with
wearying head and arms, standing at the borders of the earth ...," again
using the terms _ouranos_ and _gaia_. So the notion that this Titan was
a 'load-bearing component' of the heavenly vault may be a few
generations later than his general association with the function of
separating the earth from the sky, but these are both quite early
conceptions none the less.


1. Book I, line 54. Greek texts and translations from the Perseus site,

http://perseus.mpiwg-berlin.mpg.de/cache/perscoll_Greco-Roman.html.

2. Lines 516-7.

--
Odysseus